Related Stories

A vaccine against the sexually transmitted infection chlamydia could wipe out the disease even if the vaccine is not perfect at protecting against infection, according to Australian researchers.

According to a paper presented today at the Australasian Sexual Health Conference in Perth, the researchers predict that a 100% effective chlamydia vaccine could eradicate the infection within 15-20 years.

Using data on the prevalence of chlamydia, how it is spread, and the sexual behaviour patterns of a typical heterosexual community, Dr Richard Gray and colleagues were able to create a model that they then used to predict how different styles of vaccine might work.

They add that a less protective vaccine, which makes a person less infectious or shortens the duration of the disease, could still have a dramatic effect on infection rates.

The model also examined the effect of vaccinating just women, or both men and women.

"But if at all possible, we should also vaccinate men as well as women because it also has an indirect protective effect."

Reversing the trend

Chlamydia is the most frequently reported sexually transmitted infection in Australia, and infection rates have skyrocketed from around 9000 cases in 1997 to more than 52,000 cases last year.

It can lead to pelvic inflammatory disease in women and is associated with an increased risk of infertility, ectopic pregnancy and chronic pelvic pain.

Dr David Wilson, a co-author of the study and head of mathematical modelling of infectious disease at the Centre, says there is currently no chlamydia vaccine available, and nor has one yet been tested in humans.

Another option for tackling the rising number of chlamydia cases would be screening programs, but this is complicated by the fact that up to 80% of infected people are asymptomatic - show no symptoms.

While Dr Wilson stressed that screening was still an essential part of a public health strategy for chlamydia, the fact that people who are diagnosed and treated can still get reinfected meant a vaccine was the only option for the long term.